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Roller coaster weekend

November 16, 2012

Roller coaster weekend

A low pressure system brought strong southeastern winds to the state
late Saturday, November 10th (Anniversary of the sinking of the Edmund
Fitzgerald on Lake Superior in 1975), raising both temperatures and
dewpoints to record-setting levels. MSP airport set a new high dewpoint
record with a reading of 56 degrees F (breaking the form record of 55
degrees F in 1909) at 4:00 pm in the afternoon and also set a new high
temperature record with a reading of 69 degrees F. It was the warmest
November 10th since 1999. Several other Minnesota communities set
record high temperatures that day as well including 75 degrees F at
Rochester and Winnebago, 74 degrees F at Waseca, Fairmont (tied record),
Albert Lea, and Wells, 72 degrees F at Zumbrota, Grand Meadow, and
Preston, 71 degrees at Red Wing, 70 degrees F at Redwood Falls (tied record), 68 degrees F at Minnesota City, and 67 degrees F at La Crescent.

By
evening thunderstorms had developed in many areas delivering up to 0.50
inches of rain in some places. Three rare November EF-0 tornadoes
(winds 65-85 mph) were reported by the National Weather Service, one
near Burnsville, another in Eagan, and a third around Mendota Heights.
These tornadoes caused damage to many trees and also knocked down some
power lines. In addition some straight line winds caused damage to
trees as well. This incident was only the 4th time in Minnesota history
that tornadoes have been documented in the month of November, and the
2nd latest fall date for such an occurrence. The others were: November
16, 1931, November 2, 1938, and November 1, 2000.

Following the passage of the cold front on Sunday, November 11,
temperatures fell by over 40 degrees F in 24-hours (Rochester went from
75 F to 28 F) and many observers reported measurable snowfall, for the
most part less than half an inch. Some observers reporting significant
snowfall this week included 1 inch at International Falls and Grand
Rapids, 1.5 inches at Cook, 1.7 inches at Moorhead, 2 inches at Lake
Kabetogama, and 3.0 inches at Red Lake Falls. In the Twin Cities Metro
Area, snow and ice caused many accidents on Monday morning (Nov 12).

On
Monday (Nov 12) some observers reported daytime highs in the teens and
twenties F, over 20 degrees F below normal. Fortunately the cold snap
was short-lived and by Tuesday and Wednesday temperatures returned to
near seasonal normals. Nevertheless the cold snap froze some soils down
to 2-3 inches, and thin coats of ice began to form on many inland
lakes. Friday morning brought the first single digit temperature
readings of the fall season with 9 degrees F reported at Embarrass,
Floodwood, Orr, Crane Lake, Cotton, and Hibbing.

Little change in drought status

Despite some reports of rain and snow this week, there is little change
in Minnesota's drought status. Over 40 percent of the state's landscape
remains in severe to extreme drought, with the most notable areas in
northwestern and southwestern counties. Most observers reporting over
an inch of precipitation so far this month are not in the
drought-stricken areas of the state. These observers include Orr, Cook,
Tower, Leech Lake, Silver Bay, Cloquet, La Crescent, and Caledonia.
Unfortunately little moisture improvement is seen in the near future as
the outlook through next week favors a warm and dry pattern across the
state.

Follow up on Kuehnast Program

Approximately 250-300 people attended the Kuehnast Program's
"mini-climate school" last Thursday (Nov 8) to hear presentations about
Canada's climate, urban climates, and climate change implications for
severe weather. Information for those who missed the program can be found here.

New Seasonal Climate Outlook

New seasonal climate outlooks were released by the NOAA Climate
Prediction Center on Thursday this week. For the December through
February period they call for below normal temperatures across the high
plains and western Great Lakes states, including Minnesota. This is
based on some dynamical models as well as a persistent negative phase in
the Pacific Decadal Oscillation (PD)), a measure of disparity in the
sea surface temperature of the north-central Pacific Ocean and the
eastern sections of the north Pacific around the Aleutian Islands and
the Gulf of Alaska that persists for decades. You can read more about
this here.

The precipitation outlook for remains one of equal chances for above or
below normal values covering the December through February period.

Weekly Weather potpourri

NOAA announced this week that through new data sharing agreements it
will have access to wind data collected by two of the nation's largest
wind generator power producers in Oregon and Florida. These data will
assist NOAA scientists in fine tuning forecast models. You can read
more about this arrangement at the NOAA web site.

In South America where summer is approaching parts of southern
Argentina reported high temperatures of 95-100 degrees F this week.
These temperature values are on the order of 15 to 30 degrees F warmer
than normal for this time of year.
A paper published in the
current Bulletin of the American Meteorologist Society documents how the
convective thunderstorm flash flooding in the high Himalayan desert
during August of 2010 (8 inches or more of rainfall) was similar in
dynamical characteristics to the famous flash floods in the USA at Big
Thompson Canyon (CO) in 1976, and in the Black Hills of South Dakota in
1972. Satellite derived characteristics in these storms that are
similar may help forecasters predict such storms in the future. You can
read more here.

The World Weather Observations (WOW) web site operated by the United
Kingdom Met Office is gearing up to expand their worldwide weather
monitoring. You can view current observations from their network here.

MPR listener question

Was the interval between the Twin Cities tornado reports of Saturday
night (Nov 10) and the measurement of subsequent snowfall in the area a
record short one? Has this ever happened before?

Answer: The
tornadoes occurred on Saturday night (Nov 10) near 11:00 pm, with a
temperature of about 66 degrees F and a dewpoint of 55 degrees F. A
little more than 12 hours later (11:40 am Sunday, Nov 11) the
temperature was 30 degrees F with a dewpoint of 27 degrees F and a trace
of snow was being reported. In another 24 hours 0.2 inches of snow was
reported and the high and low temperature were 27 degrees F and 19
degrees F, respectively. Scanning the climate records for the Twin
Cities I can find nothing analogous to this rapid shift from tornado
occurrence to snowfall. The closest analogy for the Twin Cities is from
November 16, 1931 when a tornado occurred near Maple Plain, and two
days later the observer there reported a trace of snow. Elsewhere there
are only two similar stories: On March 21, 1953 a tornado was reported
near St Cloud, MN, and two days later on the 23rd St Cloud reported a
low of 21 degree F with a trace of snow; and March 18, 1968 a tornado
was reported near the Watonwan and Martin County border, followed three
days later on the 21st by a trace of snowfall in the area.

MPR listener question

I wondered why the National Weather Service uses average temperatures
from only 30 years to define what is "normal" for a location? Why not
longer periods of time?

Answer: This standard period length for
averaging climate measurements is mandated by the World Meteorological
Organization (WMO) for all government weather services. It is the
minimal period of time required to provide meaningful statistics, but
more importantly it helps to maximize the number of climate stations for
which averages can be computed. This is especially important for
countries that do not have lengthy climate records. This standard helps
scientists compare the averages from climate stations over a wide
geographic area. In Minnesota we do have some community climate records
that go back well over 100 years.

Twin Cities Almanac for November 16th

The average MSP high temperature for this date is 42 degrees F (plus or
minus 12 degrees F standard deviation), while the average low is 26
degrees F (plus or minus 10 degrees F standard deviation).

Average dew point for November 16th is 27 degrees F, with a
maximum of 59 degrees F in 1931 and a minimum of -10 degrees F in 1959.

All-time state records for November 16th

The state record high temperature for this date is 75 degrees F at
Marshall (Lyon County) in 1939, at Wheaton (Traverse County) in 1953,
and at Marshall and Milan (Chippewa County) in 2001. The state record
low temperature for this date is -27 degrees F at Big Falls (Koochiching
County) in 1933. State record precipitation for this date is `4.10
inches at Two Harbors (Lake County) in 1909; and the state record
snowfall for this date is 18.0 inches at Fairmont (Martin County) in
1909.

Past Weather Features:

One of the snowiest
mid-November periods in state history occurred over the 13th to the 16th
in 1909. Many observers reported 6 to 12 inches, and some received up
to 20 inches. Over 20 inches fell at Fosston and Fairmont.

November
16-17, 1911 brought 2 to 8 inches of snowfall to eastern Minnesota
communities, including the Twin Cities area. Following the snowfall
temperatures fell into the single digits F.
Well after dark, at
9:35 pm on November 16, 1931 a tornado touched down in Hennepin County
near Maple Plain. It pack winds of 113-157 mph (F-2) and was on the
ground for 5 miles. All barns and outbuildings of one farm were
destroyed by these winds. This remains the latest fall season tornado
ever reported in Minnesota.

November 16, 1933 brought arctic cold
air to the state, as 36 communities saw the thermometer fall below 0
degrees F with daytime highs just in the teens F. Fortunately by
month's end 50 degrees F returned to many places providing some relief
from the cold.

Over November 15-16, 1939 a spell of Indian Summer
weather prevailed as most observers reported daytime highs in the 60s F.
Six communities topped out at 70 degrees F or higher. It was
generally a warm, sunny, and dry (5th driest in state history) November
that year.

November 15-17, 1953 was the warmest such period in
state history. At least 36 Minnesota communities reported daytime highs
of 70 degrees F or higher. It was the last gasp of mild fall weather
as snow dominated the Minnesota landscape from November 20th to 30th.
Some observers reported at least a trace of snowfall everyday during
that interval.

A major winter storm crossed the state over
November 15-17, 1996 bringing a mixture of rain. freezing rain, sleet,
and snow. Some areas of northwestern Minnesota received over a foot of
snow, while heavy rain fell in eastern sections of the state, setting
record amounts in some cases. Many observers reported over a month's
worth of precipitation, 2-3 inch amounts. Bruno, Santiago, and Wolf
Ridge reported over 4 inches in one of the wettest periods in November
history.

One of the mildest mid-November periods occurred over
November 10-18, 2001 with many daytime temperature reaching the 60s F.
Dew points were summer like as well ranging from the 50s to lower 60s F.
Many golf course were open for business.

Outlook

Above normal temperatures are expected to dominate the weather into the
weekend and next week, as temperatures average several degrees warmer
than average and we see frequent sunny skies. Little chance for
precipitation, except for Monday. Then dry and mild much of next week
through Thanksgiving Day.